class ListNode{

    public int val;
    public ListNode next;

    public ListNode(int val) {
        this.val = val;
    }
}


public class MyLinkedList {

    public ListNode head;

    public void createList(){
        ListNode listNode1 = new ListNode(12);
        ListNode listNode2 = new ListNode(23);
        ListNode listNode3 = new ListNode(34);
        ListNode listNode4 = new ListNode(45);
        ListNode listNode5 = new ListNode(56);

        listNode1.next = listNode2;
        listNode2.next = listNode3;
        listNode3.next = listNode4;
        listNode4.next = listNode5;

        this.head = listNode1;

    }

    public void display(){
        ListNode cur = this.head;
        while(cur != null){
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
        System.out.println();
    }

    public boolean contains(int key){
        ListNode cur = this.head;
        while(cur != null){
            if(cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    public int size(){
        int count = 0;
        ListNode cur = this.head;
        while(cur != null){
            count++;
            cur = cur.next;
        }
        return count;
    }

    public void addFirst(int data){
        ListNode node = new ListNode(data);
        node.next = this.head;
        this.head = node;
    }

    public void addLast(int data){
        ListNode node = new ListNode(data);
        if(this.head == null){
            this.head = node;
        }else{
            ListNode cur = this.head;
            while(cur.next != null){
                cur = cur.next;
            }
            cur.next = node;
        }
    }

    public ListNode findIndex(int index){
        ListNode cur = this.head;
        while(index - 1 != 0){
            cur = cur.next;
            index--;
        }
        return cur;
    }

    public void addIndex(int index, int data){
        if(index < 0 || index > size()){
            System.out.println("index位置不合法");
            return;
        }
        if (index == 0){
            addFirst(data);
            return;
        }
        if(index == size()){
            addLast(data);
            return;
        }
        ListNode cur = findIndex(index);
        ListNode node = new ListNode(data);
        node.next = cur.next;
        cur.next = node;
    }


    public ListNode searchPerv(int key){
        ListNode cur = this.head;
        while(cur.next != null){
            if(cur.next.val == key){
                return cur;
            }
            cur = cur.next;
        }
        return null;
    }

    public void remove(int key){
        if(this.head == null){
            System.out.println("单链表为空，不能删除");
            return;
        }
        if(this.head.val == key){
            this.head = this.head.next;
            return;
        }
        ListNode cur = searchPerv(key);
        if(cur == null){
            System.out.println("没有你要删除的节点");
            return;
        }
        ListNode del = cur.next;
        cur.next = del.next;
    }

    public ListNode removeAllkey(int key){
        if(this.head == null) return null;
        ListNode prev = this.head;
        ListNode cur = this.head.next;
        while(cur != null){
            if(cur.val == key){
                prev.next = cur.next;
                cur = cur.next;
            }else{
                prev = cur;
                cur = cur.next;
            }
        }
        if(this.head.val == key){
            this.head = this.head.next;
        }
        return this.head;
    }

    public void clear(){
        while(this.head != null){
            ListNode curNext = head.next;
            this.head.next = null;
            this.head = curNext;

        }
    }
}
